Field of the Invention
The invention relates to a timing belt, particularly a toothed belt, having a first end, a second end, a rear side, a front side, and having a plurality of teeth arranged on the rear side and/or the front side, wherein the first end has at least one cutaway, wherein the second end has at least one tine that is insertable into the cutaway, and wherein the first end and the second end are detachably connectable to each other by connecting means.
Timing belts and particularly toothed belts are known in many different designs. Toothed belts are positive locking driving or transporting elements that are furnished with teeth at regular intervals. Toothed belts are usually passed over a number of pulleys, wherein the pulleys may have tooth gaps, the distances between which match the distances between the teeth on the toothed belt. In this way, the teeth of the toothed belt may engage in the tooth gaps on the pulley to create a positive locking connection. By virtue of this positive locking engagement, unlike flat or V-belts, toothed belts run synchronously and the function thereof is highly efficient.
Toothed belts are often made from plastic. In order to increase tensile strength, many toothed belts include reinforcing means of metal or fibres with outstanding tensile strength. Such tensile means may be for example metal wires, which are embedded in the base material of the belt, for example plastic.
Timing belts and toothed belts are often designed as endless belts, that is to say closed belts with no “beginning” and no “end”. Endless belts have the advantage that the belt does not have a weak point and possesses exactly the same properties over the entire length thereof. In particular, endless belts have an almost constant (tensile) stiffness throughout their entire length, so that when a load placed on the belt, expansion takes place evenly over the entire length of the belt. This enables particularly effective synchronised running of the belt.
However, endless belts have the disadvantage that it can be difficult to install and remove them. In order to install or remove an endless belt, the belt must be mounted on the pulleys as a single part from top to bottom. Accordingly, there has been a long-held desire to be able to open and close such a driving belt in the same way as a buckle belt. Such a device for opening and closing a belt is also called a “belt lock”.
Description of Related Art
Options for opening and closing a belt are known for example from DE 44 42 927 A1 and DE 2 322 343 A. Both documents include similar suggestions to provide tongues and cutouts on the ends of the belt, which may then be inserted in one another. Holes are provided in the teeth and extend transversely to the longitudinal direction of the belt through the entire length of the teeth in the direction of the belt width. Locking pins are pushed through the holes to create a positive locking connection between the two ends of the belt.
Another belt lock is known from DE 10 2004 025 170 A1. Here too, it is suggested to provide tongue/cutout-connections on both ends of the toothed belt. Circumferential grooves are formed in the connectors. Elastic connecting clamps made from sheet metal are designed to reach around the connectors, engage in the grooves, and in so doing connect the two ends of the toothed belts in positive locking manner in the area of the connectors.
A further known option for connecting the two ends of the toothed belt is illustrated in FIGS. 1, 2A and 2B, and is explained in greater detail in the section of the description reserved designated therefor.
A drawback associated with the belt locks described is the fact that the area around the lock of the belt does not have any continuous tension members, and therefore has less tensile strength than in the rest of the belt. Consequently, when a constant tensile load is applied, the area around the lock undergoes greater elongation than the rest of the belt. This is due particularly to the fact that the tensile elements that are essential for the (tensile) stiffness of the belt are split in the area of the lock, necessarily due to the design. However, the lock itself is not regularly able to increase the tensile stiffness to that of the rest of the belt.
Disproportionate elongation of the belt in the area of the belt lock has a number of disadvantages. First, unevenly distributed elongation causes the teeth to become unevenly spaced. As a result, engagement of the teeth in the tooth gaps on the pulleys is imprecise, and surfaces become more susceptible to wear.
Secondly, uneven elongation of a belt being used for transportation causes the distances between the elements mounted on the belt to be changed unevenly under load. Such mounted elements may be for example shaped sections or adapters to which transport containers may be fastened. A problem may arise in that the mounted elements are at a constant distance from each other when the belt is unloaded, but are not at a constant distance from each other when the belt is under load. In particular, the problem may arise that the distance between the mounted elements increases at a greater rate in the area around the lock than over the rest of the belt. One of the several reasons a constant distance between transportation containers under load is desirable and necessary is therefore to ensure that the containers can be loaded and unloaded reliably.